Acromioclavicular (AC) Joint Disruption
Injury to the acromioclavicular joint and its stabilising ligaments, from mild sprain to complete dislocation.
Anatomy that matters
- AC ligaments: control anteroposterior translation.
- Coracoclavicular (CC) ligaments (conoid and trapezoid): control vertical translation.
- Deltotrapezial fascia: adds stability.
Mechanism
- Direct fall onto the point of the shoulder with the arm adducted (most common), or a tackle
- Fall on an outstretched hand (indirect)
- Sports: rugby, American football, ice hockey, cycling, skiing, motocross, martial arts
- Risk: contact sports, previous AC injury, high-speed falls
Presentation
- Pain and tenderness over the AC joint, worse overhead and with resisted shrug
- Step deformity or prominent distal clavicle in higher grades
- Cross-body adduction (scarf) test positive. Paxinos sign and O’Brien’s test may also be positive.
- Skin tenting over the clavicle threatens an open injury and is urgent.
- Imaging: AP and Zanca view X-rays. MRI for associated pathology.
Rockwood classification
| Type | AC lig | CC lig | CC distance | Management |
|---|---|---|---|---|
| I | Sprained | Intact | Normal | Non-operative |
| II | Torn | Sprained | Under 25% increase | Non-operative |
| III | Torn | Torn | 25 to 100% | Controversial, individualise |
| IV | Torn | Torn | Clavicle displaced posteriorly | Surgery |
| V | Torn | Torn | Over 100% (deltotrapezial fascia detached) | Surgery |
| VI | Torn | Torn | Inferior, subcoracoid (rare) | Surgery |
Type III is the genuine controversy. Trial conservative care first, even in athletes, and reserve surgery for high-demand overhead athletes or workers, and for persistent pain or dysfunction. ISAKOS subdivides it into IIIA and IIIB to guide decisions.
Management
- Types I to II: short sling (up to 2 weeks), ice, analgesia, early range of motion, progressive strengthening. Local anaesthetic or corticosteroid injection for persistent pain.
- Type III: conservative trial, surgery if it fails.
- Types IV to VI: anatomic CC reconstruction (suture-button, graft) or hook plate.
Return to play
| Injury | Timeline |
|---|---|
| Type I | 1 to 2 weeks |
| Type II | 3 to 6 weeks |
| Type III, conservative | 6 to 12 weeks |
| Post-surgical | 4 to 6 months |
Return only when pain-free with full strength. Use protective padding in contact sports.
References
- Current Concepts in Management of AC Joint Injury, J Clin Med 2024, doi:10.3390/jcm13051413
- Imaging of the AC Joint, Radiographics 2020, doi:10.1148/rg.2020200039
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Medical disclaimer: this article is general information, not personal medical advice. Always consult a qualified doctor about your own situation.